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Stage 1

Key Point:  Prior to any further discussion of longitudinal structures it is important to point out that the longitudinal structures do more than reinforce the boat.  They also reinforce the jig.  What do we mean by that?  Each individual jig station is relatively "flimsy"  The entire structure is becomes a "rigid" mold after the longitudinal structures are properly attached.  Therefore, great care should be taken throughout these next steps to ensure that that stations remain parallel, plumb and true!

Laminating the Keel

This note will be repeated at the start of each section in this method:

Note: On the first lamination, use a router with a 1/4" round-over bit to round the inside corners for the first layer only!  When you flip the boat, you will fiberglass the inside including these longitudinal structures. Glass cannot lay down over a sharp corner.  Taking this step now is FAR easier than trying to do it later when the longitudinal is in the boat!

structural_laminationFigure 1.When you rip the Douglas Fir, don't try to achieve a tight fit in the notches in the jig stations. The slots are cut a "skosh" wider than the intended width of the laminations. Remember, you want an easy time removing the jig from the hull once it is flipped. Along those same lines, it is also very important to remember to line the stringer notches of the jig stations with blue painter's tape.
Start in the back and work forward. There is no need to scarf  the individual laminations into single boards. (If you don't know what "scarfing" or more properly "scarphing" is, don't worry, we will cover that later.)  Simply cut each lamination at a 45 degree angle and stagger the joints. Figure 1. (Right)

When laminating the keel, sometimes the bends necessary can be a little difficult --- especially on smaller boats. There are three ways to create those bends.

Use plenty of clamps and simply ease the bend in place clamping the keel lamination to the Stem and Keel Pattern using the clamp holes provided. The clamping holes are in the Keel and Stem Pattern for your convenience only. As each piece of wood has different bend characteristics, there is simply no guarantee that the pattern indicates the correct number or placement of clamps. As you bend the wood, you will quickly figure out whether you need more or less clamps. If you need more than the pattern allows, simply grab some bigger clamps and clamp to the underside of the pattern. Take your time and the wood will most likely take the bend. If not, you can decide on either (or both) of the other two methods.

If you have access to a bandsaw, resaw the wood to thinner laminations. It could also be done with a thickness planer but that would just be a terrible waste of wood. Once it is resawn to a thinner dimension, dress it with the planer.

Another method is steam.  

Side Note: Professional boat boat builders who use the cold-mold process, rarely (or never) use steam when bending these structures.  This has caused some criticism on public forums, of amateurs (and some of our builders) for using this "crutch".  Some go so far to say that steam has no place in cold-mold boatbuilding.  We feel differently about this topic.  We have a great many first-time boatbuilders who can benefit from certain techniques that reduce frustration.  Breaking wood can be frustrating.  The key point is not to encapsulate the wood until it has returned to its natural moisture equalibrium.  To determine this, buy a moisture meter (these days they are relatively inexpensive) and check (and note) the moisture level both, before and after steaming.

Steam has long been used to soften wood for bending. Steam boxes do not have to be sophisticated. Create an enclosure from tubing or four pieces of wood glued and screwed together that is long enough to enclose the pieces to be bent. A propane turkey fryer is a perfect heat source. Even a large tea kettle is sufficient to produce enough steam to bend a piece of wood. Run a tube from the kettle to the box, put in the piece of wood and close the box.  The box cannot be airtight or you run the risk of creating a steam "bomb".  There are many plans and ideas on the Internet for steam boxes.

For ¾” (19mm) wood, it doesn’t require a lot of heat or a lot of steam.

Experiment with some scrap wood to determine how long the wood needs to be exposed to the steam to turn plastic. When the wood reaches the correct exposure to heat and steam, it will significantly soften. If you haven’t steamed before, it will surprise you how much it will soften. You are most likely be steaming Douglas fir and certainly not oak but, just for illustration purposes, old-time boatbuilders would steam oak and tie a board in a knot.

Remove the board when it softens and clamp it to the Keel and Stem Pattern. Let it cool. When you remove the clamps to prepare to glue it to additional laminations, you can expect some “springback” to occur. This is nothing to worry about. When you glue it in place with epoxy into a laminated structure, it will remain in the proper shape.

Laminating the Stringers

This note will be repeated at the start of each section in this method:

Note: On the first lamination, use a router with a 1/4" round-over bit to round the inside corners for the first layer only! When you flip the boat, you will fiberglass the inside including these longitudinal structures. Glass cannot lay down over a sharp corner. Taking this step now is FAR easier than trying to do it later when the longitudinal is in the boat!

If you have read, Laminating the Keel, then you already know how to laminate stringers. There is one big difference however, stringers are MUCH EASIER! Stringers have far less bend requirement than the keel.

The only thing to be careful of is that you leave enough extra wood forward to properly shape the stringers where they meet the chinelogs. You have probably noticed that a great deal of wood gets shaped away from from the bottom outside edges of the stringers. This is most true on boats with more deadrise. Our specifications for stringer lamination tell you to laminate the entire width for each layer. This is for stated for the sake of simplicity. This leads many builders to ask: "Can I use narrower and narrower pieces for the final layers because most of it is shaped away anyway?"

The answer is... "If you clearly understand the end result required, then Yes."

Getting Started

When you rip the Douglas Fir, don't try to achieve a tight fit in the notches in the jig stations. The slots are cut approximately 1/8" wider than the intended width of the laminations. Remember, you want an easy time removing the jig from the hull once it is flipped. Along those same lines, it is also very important to remember to line the stringer notches with blue painter's tape.

Start in the back and work forward. There is no need to scarf the individual laminations into single boards. Simply cut each lamination at a 45 degree angle and stagger the joints.

Laminating the Chine Logs

A frequent question we get has to do with the area where the stringers meet the chinelog. The stringers should be laminated long and then cut and notched around the chinelog. You will be able to see the proper length and the characteristics of the notch clearly when you bend in the first layer of chinelog. The chinelog notches are set into the jig stations in a manner where the wood "wants" to bend into the appropriate shape. The side effect is there is a lot of wood to shape away. Designing the notches in this manner costs a little extra in wood but it drastically reduces or eliminates the hassles of trying to bend a fairly big piece of wood in two directions.

This note will be repeated at the start of each section in this method:

Note: On the first lamination, use a router with a 1/4" round-over bit to round the inside corner for the first layer only! When you flip the boat, you will fiberglass the inside including these longitudinal structures. Glass cannot lay down over a sharp corner. Taking this step now is FAR easier than trying to do it later when the longitudinal is in the boat!

If you made your own Keel and Stringers, by now you know how to laminate a structural component. If you bought the FasBuild Keel and Stringers, then this is your first significant lamination.   As stated, a great deal of wood gets shaped away from from the chinelogs.  Our specifications for chinelog lamination tell you to laminate the entire width for each layer. This is for stated for the sake of simplicity. This leads many builders to ask: "Can I use narrower and narrower pieces for the final layers because most of it is shaped away anyway?"

Once again, the answer is... "If you clearly understand the end result required, then Yes."

Most of our jigs feature horizontal components (we call a Vee, because of the shape) that are inserted into the keel and stem pattern.  These allows you to accurately place the first layer of the chinelogs into their proper position where they join the keel.

Installing the Gunwale Band or "Clamp"

The Gunwale Clamp is a piece of wood, typically 1-1/2 inches thick, cut straight that slips into notches in the aft sections of the jig. This provide a gluing "corner" between the plywood forming the hull sides and the deck.

It installs prior to the Sheer Clamp, providing a surface to attach the after end of the Sheer Clamp.

It should be long enough to extend forward of the location of the sheer break allowing a piece of wood to be hand fitted and glued between the Sheer Clamp and the Gunwale Clamp providing additional reinforcement of this area.

Laminating the Sheer Band or "Clamp"

The Sheer Clamp forms one of the most important shapes in the look of your boat.

It often presents a bit of a challeng depending on the degree and amount of "break" in your design. At the location of the sheer break, the sheer clamp is required to simultaneously curve in two directions. this presents a challenge for the average piece of wood. The best method to make this happen properly is "kerfing".

Installing the Ribbands (Battens)

The first thing you have to do is join sections of wood into long enough lengths so that you can place each batten into the jig as a single component.

Ribbands / battens are, most likely, the only components in the boat that require scarphing (scarfing). Scarphing???

Scarphing is the process of joining wood end-to-end in a manner that minimally compromises strength. There are many variations but the one that will be created by the jig we provide is the simple scarph, an 8:1 angled lamination between two pieces of wood. 8:1 means that the length of the angled portion is eight times the wood thickness.

The supplied scarphing jig is comprised of 3 parts. Two angled rails and a base. Glue the rails into the dadoes machined into the base so that the short end of the rails are placed toward the edge of the base. Now it is ready to use.

Here is how it works.

Clamp the base to your work bench. Mount 1/2" template guide bit in your router and ensure that it is extended far enough to cut through a 3/4" thick piece of material. Now, plug in the router, turn it on and slide the base of the router down the rails until the bit begins to strike the base. now slide the router across the jig scoring the base. That is the endpoint of where to clamp the piece being routed. Now, insert the first piece of wood to be scarfed with the end of it just past the scored line you just made. Start the router and slide it from the top of the rails toward the bottom easing it into the wood. Don't be too agressive. Take it easy and make a smooth cut. Continue this process sliding up and down the rails until the entire piece is machined. You now have an 8:1 angle. Do the same on another piece of woood and you can now glue the two together with almost the strength of the unjoined wood. For ribbands / battens, this is all you need.

To glue them together, make yourself a little assembly jig. (Or three of four) Take a 36 inch piece of 3/4" plywood and rip it to a width of about 4 inches. This is the "base" of your assembly jig. Rip another piece 1 inch wide. Glue and screw it on top of the 4 inch base with the edges aligned. This forms the "fence" of the assembly jig. Next, cover the base and fence with packaging tape to ensure that the scarfed ribband does not stick to the assembly jig.

Screw the first piece to be joined on top of the jig and tight against the fence with the joined portion roughly centered on the 36 inch length.

Mix up some thickened epoxy and spread it on the surfaces to be joined. Screw the second piece in place and drive one screw right through the middle of the joint. Let the epoxy harden and you now have one long piece of wood.

Installation

Most people find it easier to install them starting aft and working forward. Remember to extend them sufficiently to ensure that you initially have excess material beyond where the transom will be placed.

The notches are intentionally cut large enough to ensure that the ribbands "float" in the notches. This way, they are manually adjustable such that no shaping is required to make their outer surface match the hull. Simply manipulate them manually and, when they are in the correct position, attach a bracket on the inside such that all screws can easily be removed from the inside after the boat is flipped.

Remember, (even though you LOVE our jigs) you probably want to remove the jig from the boat at some point in time. w00t

Install one on each side of the jig station for additional strength wherever the bent plywood puts significant stress on the brackets. These are typically forward where you are bending the plywood around to form the bow (with that beautiful flare) and aft near the sheerbreak where the flare eases out of the boat.

Fabricate the brackets quickly and cheaply yourself. At your local DIY store, buy as many "sticks" of aluminum angle as it takes to make the brackets for your model.

The key information about the "stick":

  • Aluminum Angle
  • 1 inch 'legs'
  • 1/8" thick
  • Typically, 8' long

To make them...

bracketsFigure 2.
Set up a stop on your chop-saw in order to quickly cut the stick up into 2" lengths. (Wear your safety glasses OF COURSE!)

Next, drill one 3/16" hole in the center of one leg and two 3/16" holes approximately 3/8" in from each end on the other leg. (Figure 2.)


You might want to make a little fence with stop on your drillpress to make this operation quick and foolproof.

When you get to the forward sections of the jig, the ribband must bend and also "roll". This might require a bit of help to hold it in place as you attach the brackets. It works best to attach the bracket to the ribband first before trying to "roll" the ribband. Once it is held in its proper position, drive two screws through the bracket into the station.

One leg of the bracket (attached to the station) has two holes to keep the ribband from "rolling" back.

Note: Most ribbands do not meet the station at a right angle. Be careful when driving the screws into the station not to overtighten them. This will avoid deforming the fair curve described by the bent ribband!

Don't be tempted to just go by a bunch of pre-made steel angle brackets. 

  • They are expensive.
  • They don't work as well. (They are soft and bend easily)

Most of our jigs feature horizontal components (we call a Vee, because of the shape) that are inserted into the keel and stem pattern.  These allows you to accurately place the ribbands into their proper position where they join the keel.

 
Last modified on 08-12-13
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